Automatic reclosing electric circuit interrupter



L. S. WALLE May 23, 1950 AUTOMATIC RECLOSING ELECTRIC CIRCUIT INTERRUPTER Filed July 12, 1949 Inventor: Ludwig SWaHe,Y

His Atorneg.

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coming conductor I is attached. Bimetal Ii] is fastened by means of a cap screw 4I to a piston IB which is adapted to move vertically within the bore of cylinder 4. Piston I6 is normally biased by gravity to the lowermost position against shoulder I3 Within cylinder 4. Within piston I6 is a chamber Ia which is partially filled with metal pellets I'I. The weight of the piston may be adjusted as desired by changing the number of metal pellets I'I. Thus the op-v erating characteristics of the breaker may be adjusted, as will be more fully explained below. Since the support partition I2 for bolt I I, bimetal 9 and contact B, and piston I6, which supports bimetal I0 and contact 'I, are both normally positioned against shoulder I3, the axial length of shoulder I3 determines the normal contact spacing. Cylinder 4, partition I2, and piston I3 enclose a chamber 24 containing the contacts 6 and 'I, their supporting members, and insulating fluid such as oil. Bimetal I0 is connected to piston I6 through a tube I8 of electrical resistance material, such as an alloy consisting of nickel and chromium, which extends through the center of piston I6, the purpose of which will be explained below. Tube I8 is surrounded by an asbestos heat insulating tube 4i). At the upper surface of piston I6, outgoing conductor 23 is connected to the upper end of resistance tube I8 through a piston cover plate I6b. Thus, the electrical circuit through the circuit interrupter is through conductor I5 to bolt II, through bimetal 9, contacts 6 and 1, bimetal I6, resistance tube I8, and outgoing conductor 23.

Under operating conditions my circuit interrupter is normally at rest in the position shown in Fig. 1. If an excessive electrical current is conducted through the interrupter, bimetals 9 and I are heated thereby and one or both of these bimetals snaps into the position shown with dotted lines in Fig. 1. These bimetals will snap because of their concavo-convex, or dished, shape, the concavity of said bimetals reversing as they snap so that after snapping open, bimetal 9 is concave downward and bimetal I is concave upward. When either bimetal 9 or I0 snaps, contacts 6 and I.are thereby separated by a small gap, thus causing an electric arc between them. The oil in the immediate vicinity of the arc is thereby heated and vaporized, creating a pressure within chamber 24. v The vapor is generated very quickly and the pressure produced thereby is not dissipated immediately through the lower Vent 5, but forces piston I5 upwardly until it reaches a stop 36, or until contacts 6 and I are separated to an extent sufficient to extinguish the arc, after which the pressure subsides. Stop 3S may be provided with a resilient buffer (not shown) to absorb the shock of stopping piston I6. The movement of the Vapor through vents 5 to exhaust the pressure within compartment 24 assists in extinguishing the arc because the l ionized gases through which the arc is passing are moved toward vent 5 and the arc itself is, therefore, moved in that direction and thereby lengthened, and relatively cool, unvaporized oil is also forced between the arcing contacts in the path of the arc.

When the arc is extinguished, piston I5 returns to the position shown in Fig. 1 under the bias of its own weight. After a predetermined time, bimetals 9 and I0 both lose the heat acquired in the original overload, and snap back from the position shown with dotted lines in Fig. 1

to the position shown with solid lines. Thus..

the circuit interrupter is reclosed after a predetermined period of time during which the condition in the circuit causing the excess current may be corrected. If upon the reclosure of contacts 6 and 'I the fault or overload condition is still present, the circuit interrupter will repeat the previous interruption cycle. A small pressure relief hole (not shown) may be provided in the upper portion of casing 2 to relieve oil pressure due to repeated interruptions.

. After a number of these interruption cycles the following structure becomes operative.

` Within the electrical resistance tube I8 on piston I6, a lockout bimetal I9 is fastened by rivets 35 so that heat generated by the electric current in resistance tube I8 may be thermally conducted into bimetal I9. Bimetal I9 extends upwardly beyond the top of piston IS, and at the upper end thereof is a latch member 2U. A reset shaft 2I of triangular cross-section is rotatably mounted horizontally in the upper portion of casing 2 in a position where said shaft may be engaged by latch member 20 when piston I6 is in its elevated position and bimetal I9 is in its deflected position as shown dotted in Fig. l. This shaft, or its equivalent in this latch-engaging function, may sometimes be hereinafter referred to as a latch-engaging member when latch member 20 thusl engages reset shaft 2|, as shown in Fig. 3, the circuit interrupter is locked open. Bimetal I9 is not deflected sufiiciently to cause latch member 20 to engage reset shaft 2l until after a predetermined number of the circuit interruptions previously described. When such a degree of deflection of bimetal I9 is obtained, upon the next elevation of piston IS, latch member 20 engages the lower surface of reset shaft 2| as shown in Fig. 2 and bimetal I9 is thereby deflected to the right, allowing the latch member 2E) to pass upwardly past reset shaft 2|. This latch then engages the upper surface of such shaft when piston I6 begins its return stroke.

At one end of reset shaft 2I is a reset arm 22 by which the shaft may be rotated manually by use of a disconnect hook or switch pole 3l. When my circuit interrupter is once locked in the open position, it will remain in this position until a maintenance employee uses switch hook 31 to rotate reset arm 22 to rotate reset shaft 2I to release latch member 20. Before this occurs bimetal I9 has cooled sufficiently that the bimetal will be biased to return to its normal vertical p0- sition when latch 20 is released from reset shaft 2 I. This release action is shown in Fig. 4. Upon such release, piston I6 descends to its original position and contacts 6 and 1 again close, thus re-establishing the original circuit through the interrupter.

In certain applications of my invention my circuit interrupter may be subjected to mechanical shocks which would tend to disengage latch 20 from the reset shaft 2l. I may, therefore, use an alternative structure shown in Fig. 6 wherein the shaft or pivot 2I is shifted nearer to the center of reset arm 22 in order to reduce the tendency of this arm to rotate under shock conditions. Latch 20, in this embodiment, has been changed in shape to have a more positive retaining action in cooperation with a separate latch engaging member 43.

On the descent of piston I6, it may occur that oil will be entrapped in chamber 24. However, this oil may be displaced by the piston and the oil level adjusted by reason of an orifice 38 through resistance tube I8 through the center of the pisj eerewfar isa-lso provided for purpose.

ifather lpressureegenerating #means responsive as"theyinitiallyfseparate'may-1begused 'in place :of

the^oi whiehfiadescribedeabove. *For example.

certain solid #insulating `materials i 'such-A -as hard couldJ bei lined-with 'suchal-zmanterialwhich-would lTheuse ofesu afsolid-gasfprdducing insulating material @in #electric circuit iinterrupters its shown,A lfor instancefinPatent `"2 ,1458 ,i3 r7.1 issuedto Bellen-j Towerano lBenja-min ssn-een, ein, and assigned; tolthe same assignee' ask the* v'present-ap- -v plication.

`'iin order fte' prevent rotationdf"'piston` l 6` :asit

A'My complete circuit mterrupter structure adapted fffor mounting V4as fa unit on a *wooden* cross arm'offffafconventional Y low voltage` transmissionfpole. The steel tank`- 2 provided with studs -26 toifthe breaker tank. The-cover structureis vprovided 'with downwardly extending lateralextensionsf in whicheare mounted the leadinsu-latingbushingsxl8 for the line" conductors leand 23.- The insulatorsarersuitably mounted andffsealed,as==at30, so l:as to-sealthe #breaker andv secured, --'as1atl32,'- to the cuyer-"structure vfor facilitating inspection. --A pair of supporting lugs 33 are secured to the cover structure so that the breaker as a unit `may zbesuspended; from or slung beneath the pole cross arm.

While I have described and illustrated a pre ferred embodiment of my invention, it should be understood that I do not intend to be restricted solely thereto but I do intend to cover all modications thereof which would be apparent to one skilled in the art and which come within the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. An electric circuit interrupter of the reclosing type including an enclosed container and a. temperature responsive gas generating substance and a reciprocable piston within said container, a thermally responsive current carrying member attached to and movable with said reciprocable piston, separable contacts, one of which is attached to said thermally responsive current carrying member and adapted to be separated thereby to initiate an electric arc to heat said temperature responsive gas generating substance to thereby generate a gas to cause a pressure within said container which forces the reciprocable piston and the attached thermally responsive current carrying member upward to increase the separation between the respective contacts and interrupt the electric circuit, said container having an exhaust opening in the lower end ton.v orifice i452 through*itl-ie i center ofaeabv cover lstructure'l zisuitably-lseeured, ivas=lby fscrew thereon-to aiiewthe escapeef-ethefgas forsafd piston *torreturn `to *its "original `ip'osition, ssaid" therr'nally "responsive member also Ireturning i to its Jorigina-l position v"to yfre-establish the electric circuit afterapredetermined' timedelay" interval duringwhich said "thermally responsive member returns A"to j 'substantially its-former i temperature, and 'afthermally v"responsive "lockout Ymem-ber adapted aftera predeterminedl numb er' circuit interruptions' to retairrsai'djpiston'inthe 'elevated position.

"2.1 electric circuit :interrupter of the reclosa ingY type includingan 'enclosedf container partially nlledwith avaporiz'ab'le insulatingliquii'a 're" c'iprocable 4pistoniwithin.'said container, a jthermally responsive `current lcarrying member at'- tached 'to :and movable with ',sa'id reciprocable piston, "separable 'contacts 'one of 'whichis attached 'to said "thermally responsive 'current carrying member rand adapted' to'be separate'd thereby' t`o"initiate 'an electric arc'to Vvap'orize a' poi-tion of' the insulating li'quid'to ca'use a pres' surewithin said container'whichforces the 're-' ciproca'ble piston 'and the attached 'thermally responsive current 'carrying member upwardt'o increase the 'separation' between the respective contacts and' interrupt the electric circuit, "said container having an exhaust .opening 'in' the lower end thereof' to allowk the escape of. the vapor "for saidfpiston 'to `return to .its Driginalfpo'sition, said thermally 'responsive member'al's'oreturning to its original positionA 'to 'reesta'blish the electric circuit after a predeterminedtime delayinte'rval du'ringrwhichrfsaid' thermally 'responsive j'member returns to substantially its` ifonrrer temperature, ajthermally 'responsive'lockut 'member adapted after a ,predetermined number f circuitinterruption's to 'retain 'said piston `inthe elevated position.

3. electric circuit 'interrupter,of-thareclosing 'type comprising a casing,1co.acting relatively movable contacts Asupport'ed on current` carrying v snap-actingbimetallio elements and Yarranged to initially separate within an.'` insulatingv liquid yin the lower part. 'of saidhca'sing Ywhen said bimetallic elements. are heated 'by an `overload current,A a f pi'stor within'sa'id casing vertically reciprocable between a lower position in which the interrupter is normally closed and a raised position in which the interrupter is open, one of said bimetallic elements being supported on said piston, said piston being biased downwardly by its own weight and adapted to rise vertically under the force of oil .vapor generated by an electric arc which occurs -cuit interruptions initiated by said bimetallic elements to retain said piston in the raised position, said latch engaging member being rotatable to release said latch member.

4. An electric circuit interrupter of the reclosing type comprising a casing, coacting relatively movable contacts supported on current carrying snap-acting bimetallic elements and arranged to initially separate within an insulating liquid in the lower part of said casing when said bimetallic elements are heated by an overload current, a piston within said casing vertically reciprocable between a lower position in which the interrupter is normally closed and a raised position in which the interrupter is open, one of said bimetallic elements being supported on said piston, said piston being biased downwardly by its own Weight and adapted to rise vertically under the force of oil vapor generated by an electric arc which occurs as said contacts initially separate to thereby cause a further separation of said contacts and an extinguishment of said arc, the initial separation of said contacts being maintained upon the return of said piston to its original position to maintain the circuit interruption for a predetermined time delay period, a bimetallic lockout element supported on said piston and having a latch member on the end thereof, a reset shaft, said member being adapted to engage said reset shaft under the influence of said lockout element after a given number of circuit interruptions initiated by said bimetallic elements to retain said piston in the raised position, said reset shaft being rotatable to release said member.

5. An electric circuit interrupter of the reclosing type comprising an oil filled vertical cylindrical container, a vented cylindrical container within said iirst cylindrical container, a piston reciprocable within said vented cylindrical container, separable electrical contacts, two bimetallic thermally responsive current carrying' trip elements respectively for the support of each of said contacts, one of said elements being supported at the bottom of said vented cylindrical container and the other of said elements being supported on the lower portion of said reciprocable piston, said elements being adapted, when heated by an overload current, to snap said electrical contacts apart, thus initiating an electric arc the heat of which vaporizes a portion of said oil and thereby generates a pressure which raises said reciprocable piston, thereby further separating said separable contacts, thus interrupting said arc by the lengthening thereof and by the interposition of oil in the path thereof by virtue of the exhaustion of said vapor through the vents said elements attain a reduced temperature, said flected from said shaft, on the upward stroke of of the vented cylindrical container, said piston being further adapted to descend to the original position upon the exhaustion of said vapor, said piston being of a hollow construction and including a filler of an adjustable quantity of metal pellets for added weight to accelerate said descent at a selected rate, the separation of said separable contacts being maintained by said thermally responsive current carrying trip elements for a given time after the descent of said piston until interrupter being adapted to repeat the above interruption cycle a number of times should said overload current persist, a. thermostatic lockout bimetal attached to the upper portion of said piston and an electric current carrying resistance element associated therewith and adapted to heat said bimetal upon the occurrence of an overload current to thereby cause said bimetal to deflect, a latch member at the end of said bimetal and a rotatable reset shaft adapted to be engaged thereby when said bimetal has been deiiected and when said reciprocable piston is in the raised position, said bimetal being dellected sufficiently for this purpose only when the overload current condition persists after a predetermined number of interruption cycles, the Iupper surface of said latch member and the lower surface of said resetshaft having slanted contours which are adapted to enable said latch member to be desaid piston, said latch member then being adapted to engage said shaft on the downward stroke of said piston to retain said piston in the raised position, the upper surface of said shaft and the lower surface of said latch being slanted to prevent subsequent disengagement after said bimetal cools and thereby becomes biased towards the undeflected position, and means for rotating said shaft whereby the upper surface of said shaft may be rotated toward said bimetal to reverse the slant of the upper surface of said shaft and thereby release said latch to allow said piston to descend, reclosing said interrupter.

LUDWIG S. WALLE.

No references cited. 

